Aldosterone-induced proteins in toad urinary bladders. Identification and characterization using two-dimensional polyacrylamide gel electrophoresis.
Aldosterone-stimulated Na+ transport is mediated by new protein synthesis, but the identification of specific aldosterone-induced proteins (AIPs) has proven difficult and the cellular function of such proteins is unknown. Using high resolution two-dimensional polyacrylamide gel electrophoresis and autoradiography we have identified AIPs of similar isoelectric points (5.8 to 6.4) and molecular weights (70,000 to 80,000) in membrane-rich and cytosolic subcellular fractions of epithelial cells derived from single toad urinary bladders. The ability of actinomycin D to inhibit both AIP synthesis and aldosterone-induced Na+ transport is consistent with a role for these proteins in the natriferic action of aldosterone. In addition, since non-natriferic concentrations of cortisol did not induce similar proteins, AIP synthesis appears to be mineralocorticoid-specific. The relationship of AIP synthesis to Na+ transport was also studied. Since amiloride, which blocks Na+ transport in high resistance epithelia, did not affect the synthesis of these proteins, Na+ transport is not required for their synthesis. In addition, similar proteins were not induced when Na+ transport was stimulated by antidiuretic hormone and theophylline. Consequently, AIP synthesis is not merely a nonspecific consequence of the cellular metabolic changes associated with Na+ transport.
D000450:Aldosterone / Q000494:pharmacology*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002024:Bufo marinus; D003609:Dactinomycin / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology; D007700:Kinetics; D008970:Molecular Weight; D014176:Protein Biosynthesis / Q000187:drug effects; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*
D003609:Dactinomycin; D000450:Aldosterone; D000584:Amiloride; D006854:Hydrocortisone